Transmission/engine control system for a motor vehicle with automatic transmission

ABSTRACT

A transmission/engine control ( 1 ) for a motor vehicle with an automatic transmission ( 2 ) having a warning apparatus ( 3 ) for a disturbance of a signal transmission from an electrical position recognition apparatus ( 4 ) of a selection lever ( 5 ) which acts on the regulating device of the automatic transmission, via an electronic transmission control. The warning apparatus ( 3 ) has the purpose of notifying the driver that no further change in the direction of travel can be executed and the warning apparatus ( 3 ) coacts with a program module of a transmission independent processing unit ( 6 ) which, upon occurrence of the disturbance of the signal transmission, initiates an emergency operating mode of the automatic transmission ( 2 ) and determines a vehicle speed which is less than a specified threshold value. The processing unit ( 6 ) communicates a maximum allowable motor torque and/or a maximal allowable motor speed of rotation to a program module of a motor control ( 7 ). Alternatively, the warning apparatus ( 3 ) can provide a signal to a control apparatus ( 10 ) of a vehicle brake system for the activation of the brake system or signal to a locking apparatus ( 12 ) to lock the selection lever in its existing position, or the warning apparatus can provide the driver with an optical or an acoustic advisory indication.

FIELD OF THE INVENTION

The invention concerns a transmission/engine control for a motor vehiclewith an automatic transmission in accord with such a control moreclosely defined in the generic concept of the present patent.

BACKGROUND OF THE INVENTION

As taken from the state of the technology in the known transmissioncontrol for an automatic transmission of a motor vehicle that possessesan electrical circuitry, the placement of gear ratio position isinitiated by the options of a driver. The driver accomplishes this bymeans of activating a gear selection lever, wherein the position of thelever is detected by a position recognition apparatus which sends acorresponding signal to an electronic transmission control.

Should a disturbance occur in a signal transmission along the signalpathway between the gear selection lever and the control of theautomatic transmission, then an emergency operating mode is activated inorder to allow the automatic transmission to run a hydraulic emergencyprogram. A disturbance can come about through a dropout of a data bus ofa Controller Area Network (hereinafter, “CAN”) or in the failure of anelectronic control device, such as the electronic transmission control.

In the case of a disturbance, as a result of the then activatedemergency operating mode, no further alteration of the driving programin the automatic transmission is possible, except for stopping themotor. Normally, one gear stage becomes hydraulically fixed in anemergency operating mode. It is impossible for the driver to change thissituation by manipulating the position of the gear selection leversince, firstly, the electro-hydraulic actuator for the clutch controlcan no longer be regulated electrically and, secondly, the electricalposition recognition impulses can no longer be transmitted.

The latter, relating to the position recognition apparatus, isespecially problematic in the case of an automatic transmission with anexclusively electrical connection between the gear selection lever andthe transmission.

For example, DE-OS 196 43 812 describes a parking-block system for anautomatic transmission in which the gear selection lever is completelyuncoupled and the control demands of the lever are exclusively takenover by the electronic transmission control.

DE-PS 44 22 257 describes a gear selection apparatus for an automatictransmission wherein the stages “D”, “N”, and “R” are exclusivelyshifted in by an electric motor which is controlled by an electronictransmission regulatory apparatus. In this arrangement, only in the gearselection stage “P” would the mechanical-hydraulic coaction between thegear selection lever and the transmission be initiated.

If, by the occurrence of a disturbance of the signal transmission, agear position for forward travel is shifted, and the driver, by means ofthe gear selection lever, gives the command for change to a reversegear, this shifting order cannot be transmitted to the transmissioncontrol and carried out and the vehicle, upon starting from rest,disadvantageously travels forward contrary to the expectation of thedriver.

In order to alert the driver that the automatic transmission is in theemergency mode, as advised by the state of the technology, theinstrument board of the motor vehicle is provided with a warning elementor a light signal to indicate such disturbance. Further, another knownprocedure is to notify the driver of an activation of the emergency modeby the extinguishing of a normally illuminated display of the gearselection position display on the instrument board or elsewhere, whichis in electrical communication with the electronic transmission control.

However, this arrangement is disadvantageous because these warningdisplays only indicate a general emergency condition so that the drivercan come to a false conclusion about carrying out a change in thedirection of driving.

This can lead to a situation wherein, after a driver's movement of agear selection lever to change the travel direction of the vehicle froma “FORWARD” gear selection to “REVERSE”, the vehicle itself moves in a“false” direction upon starting.

Upon a strong activation of the gas pedal, the motor vehicle can thenrun into an obstruction in the vicinity since, in such an occurrence,the reaction time in which the driver has available to evaluate thesituation can be too short to avoid an accident by subsequent activationof the vehicle brake. Thus, the present invention has the purpose ofmaking available a transmission/engine control for a motor vehicle withan automatic transmission and an electrical position recognition of theplacement of gear selection lever with which, in the case of adisturbance of the signal transmission between the gear selection leverand transmission and in an activated emergency mode, the danger ofaccident by undesired starting from rest in a “false” direction isavoided, or at least a start of motion with only a low acceleration ispossible.

In accord with the invention, this purpose is achieved with atransmission/engine control as discussed below.

SUMMARY OF THE INVENTION

When the invented transmission/engine control is constructed, assuranceis advantageously given that in the case of a disturbance of a signaltransmission from the electrical position recognition apparatus of thegear selection lever to the control means of the automatic transmission,by means of which a disturbance in a direction of travel change can nolonger be carried out, and only a slow startup of the motor vehicle ispossible.

This is of particular advantage, if the driver of the motor vehicle isof the opinion that he has effected a change in a direction of travel bymeans of activation of the gear selection lever whereby the fact isthat, because of the disturbance, no change of the existing gear stageoccurred. With the achievement in accord with the invention, namely, themotor vehicle does not travel with its entire available motor capacity,but only with a lesser motor capacity, so the driver has sufficient timeand is able to avoid damage to his motor vehicle.

Alternative to this, the transmission/engine control can be so designedthat with this achievement of the purpose of the invention, in a simplemanner assurance can be given that in the case of a disturbance of thesignal transmission from the electrical position recognition apparatusof the gear selection lever to the regulatory means of the automatictransmission, by which no change in the direction of travel is possible,a driver can start up from still stand with the motor vehicle, having noacceleration, or with only a reduced acceleration, that is, the vehiclespeed, in what is for him a “false” direction.

By means of the activation of the vehicle brakes, in an advantageousmanner, an accident can be avoided. To accomplish this, the vehiclebrakes can be activated by a processing unit, independent of thetransmission, in such a manner that a startup of the motor vehicle is ingeneral prevented, or is possible only at a very slow speed.

With the invented achieving of the purpose of the invention which, initself alone, or in combination with one of the achievements, provisioncan be made to achieve the advantage that the driver of a motor vehiclecan be advised, through the blocked gear selection lever, that a changein the direction of the travel by means of a change of the gearselection in the automatic transmission is not possible. This wouldindicate that forward travel, subsequent to reverse travel, is notpossible. This invented advantage provides the driver with a clear, andunmistakable announcement, that a change of the travel direction is notpossible.

An optical or acoustic advisory display presents a constructive, simpleand economical advantage of the invention which can be installed on theinstrument panel.

In a development of the transmission/engine control, it can be providedthat the warning apparatus is at least activated for a specific time ofapplication.

To accomplish this, advantageously the driver is first signaled that adisturbance is in force and a travel directional change of the motorvehicle is not possible. After expiration of the time of application,the motor related or brake related operational intervention can, inpart, be rescinded by the warning so that a larger vehicle mobility ismade available and a limited continuation of travel to a repair stationis assured. This travel would take place in a hydraulic emergency modeof the automatic transmission without markedly increasing the safetyrisks to the driver.

Further advantages and improvements of the invention arise with the aidof the drawing, showing a sketch schematically based on the describedembodiment.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described, by way of example, with referenceto the accompanying drawings in which:

FIG. 1 is a schematic block-drawing of a transmission/engine control foran automatic transmission.

DETAILED DESCRIPTION OF THE INVENTION

The single Figure of the drawing shows a very schematized block-circuitdrawing of a transmission/engine control 1 for an automatic transmission2 of a motorized vehicle, not further described, whereby one warningapparatus 3 is provided which displays a disturbance of an electricalposition recognition apparatus 4 of a gear selection lever 5 on acontrol means (not more thoroughly described) of the automatictransmission. By means of the selection lever 5, several gear stages P,R, N, DI, II, III, IV can be chosen by a driver and electricallyinitiated.

The warning apparatus 3 incorporates a program module of a processingunit 6 which is independent of the transmission. Under emergency driveconditions affecting the automatic transmission 2, upon the recognitionof a vehicle speed, which is less than a specified threshold, thewarning apparatus 3 signals to a program module functioning in a motorcontrol 7. The motor control 7 is designed to coact within a DigitalMotor Electronic apparatus, and determines a maximum allowable motortorque and/or a maximum allowable rate of rotation for the motor for anemergency state operation. The transmission independent processing unit6, in the embodiment shown in the figure, is simultaneously a computerfor the motor control 7.

In another embodiment of the present invention, not illustrated, theprocessing unit 6, which is independent of the transmission, can also bedesigned as a separate control apparatus.

The automatic transmission 2 is connected by line 8A with an electronictransmission control unit 9 designated as “EGS” in the figure. Thisconnection is especially for the sending electrical control commands forhydraulic transmission regulation. The position recognition apparatus 4is connected to the transmission control equipment 9 by means of a CANdata bus 8. For communication with other control units of the vehicle,such as a control apparatus 10 regulating the vehicle brakes, theelectronic transmission control 9 is likewise connected to these bymeans of a CAN data bus 8.

In an alternative embodiment, the electrical signal transmission betweenthe electronic control units 6, 7, 9, 10 can be carried out among oneanother and for the position recognition apparatus 4 through a singlecable.

A disturbance of the signal transmission from the position recognitionapparatus 4 to the control elements of the automatic transmission 2 cantake place by a disturbance or a dropout of the electrical transmissioncontrol 9 and/or the CAN data buses 8 and/or the position recognitionapparatus 4. Under these conditions, the emergency running mode isinitiated by the electronic transmission control equipment 9. Thehydraulic control equipment in the automatic transmission 2 (not shownin more detail) activates the emergency mode program so that the motorvehicle can be driven further, at least in a limited way.

The warning apparatus 3 recognizes the emergency mode operation by thelack of a signal from the electronic transmission control 9, whichsignal denotes normal operation.

If the driver of the motor vehicle, by means of the placement of thegear selection lever 5 of the position recognition apparatus 4, sends acommand for a change of a direction of travel or to change the existingdriving program, for instance, from “D” to “I”, in the normal manner offunctioning the transmission/engine control, the chosen direction oftravel, or the chosen running program is set into the automatictransmission.

In the case of a disturbance in the signal transmission and theresulting emergency operational mode, an alteration of the position ofthe gear selection lever 5 is no longer recognized. If the driver wouldnow change the selection lever 5 from a position for forward travel D toa position R, i.e. reverse, the motor vehicle would, nevertheless,continue in its program for forward motion.

The warning apparatus 3 sends to the motor control 7 commands for amaximum allowable motor torque and/or a maximum allowable speed ofrotation. In this way, the motor vehicle can drive forward only at amarkedly diminished acceleration, with a greatly reduced traction and ata reduced speed. The quantitative value of the torque and/or rotationalrate is to be applied correspondingly, as provided in the presentembodiment, in such a manner that the vehicle can move itself only at acreeping speed, that is at 8 km/h.

In the case of a disturbance of the signal transmission, a furtherpossibility for limiting the speed of the vehicle or the accelerationduring starting from a rest position, is obvious in an embodimentpresented in dotted lines in the figure, in which the warning apparatus3, with its transmission independent processing unit 6, emits a signalto a program module of a control apparatus 10 related to the vehiclebrake system for activation of the brakes (not shown). The processingunit 6, independent of the transmission, coacts with a processor of thecontrol apparatus 10 of the vehicle brakes, which is integrated into theshown part of an anti blocking system 11.

With these variants in construction, it is likewise assured that themotor vehicle starts at a much reduced acceleration or can only be movedat low speed. It lies within the realm of the expert to provide thegripping power of the brakes by the vehicle braking system so thatstarting of the vehicle from rest is, in general, prevented.

In a further variant of an embodiment, denoted in the drawing by dottedlines, provision has been made that the warning apparatus 3, co-actingwith a locking device 12 to block the gear selection lever 5, so thatthe selection-lever is fixed in its existing position upon occurrence ofthe disturbance. In this way, the driver can no longer activate theselection lever 5 and this situation confirms, that a change of thedriving program is no longer possible.

The locking apparatus 12 is constructed as an electromagnet or permanentmagnet which fixes the selection lever in its actual position.

In the above embodiment example, the manner of functioning of thetransmission/engine control, in accord with the invention in the case ofa signal transmission disturbance and release of the emergencyoperational mode, is for a forward travel motion. Obviously, this isalso analogous to a signal transmission disturbance and release of theemergency operational mode during travel in a reverse direction.

In this case, for instance, the locking apparatus 12 blocks theselection lever in the position “R”. The described motor side and brakeside actions are independent of the selection lever position. Theautomatic transmission 2 remains hydraulically fixed in the reversegear, at least for such a time as no system reset is carried out by theshutting off of the ignition current.

Reference Numbers

1 transmission/engine control system

2 automatic transmission

3 warning program module

4 position recognition apparatus

5 selection lever

6 processor unit, independent of transmission

7 digital motor electronics

8 controller area network

8A signal bus lines

9 electronic transmission control equipment

10 control unit of vehicle brake

11 vehicle braking system ABS anti-blocking-system

12 locking apparatus

P park position of selector

R reverse position of selector

N neutral position of selector

D drive position of selector

I first gear forward

II second gear forward

III third gear forward

IV fourth gear forward

What is claimed is:
 1. A transmission/engine control for a motor vehiclewith an automatic transmission, the transmission/motor control having awarning apparatus (3) for indicating a disturbance of a signaltransmission from a position recognition apparatus (4) of a selectorlever (5), by which a desired one of a plurality of gear positions (P,R, N, D, I, II, III, IV) can be selected by a driver, the selector lever(5) acting through an electronic transmission control on a regulatingmeans of the automatic transmission; wherein the warning apparatus (3),in order to indicated that a change in a travel direction no longer canoccur, has a program module of a transmission independent processingunit (6), and said processing unit (6), upon occurrence of saiddisturbance of the signal transmission, initiates an emergency operatingmode of the automatic transmission (2) determines a vehicle speed forthe vehicle, which is less than a threshold value, and communicates toat least one of a maximum allowable motor torque, a maximum allowablemotor speed of rotation and a maximum allowable vehicle speed to aprogram module of a motor control (7) for the emergency operating modeof the vehicle.
 2. A transmission/engine control for a motor vehiclewith an automatic transmission, the transmission/motor control having awarning apparatus (3) for indicating a disturbance of a signaltransmission from a position recognition apparatus (4) of a selectorlever (5), by which a desired one of a plurality of gear positions (P,R, N, D, I, II, III, IV) can be selected by a driver, the selector lever(5) acting through an electronic transmission control on a regulatingmeans of the automatic transmission; wherein the warning apparatus (3),in order to indicate that a change in travel direction no longer can beexecuted, has a program module of a transmission independent processingunit (6), and said processing unit (6), upon occurrence of saiddisturbance of the signal transmission, initiates an emergency operatingmode of the automatic transmission (2) and determines a vehicle speed,which is less than a threshold value, and sends a signal to a programmodule of a control apparatus (10) for activation of a vehicle brakingsystem of the vehicle.
 3. A transmission/engine control for a motorvehicle with an automatic transmission, the transmission/motor controlhaving a warning apparatus (3) for indicating a disturbance of a signaltransmission from a position recognition apparatus (4) of a selectorlever (5), by which a desired one of a plurality of gear positions (P,R, N, D, I, II, III, IV) can be selected by a driver, the selector lever(5) acting through an electronic transmission control on a regulatingmeans of the automatic transmission; wherein the selector lever (5)includes a locking device (12), and the warning apparatus (3), in orderto indicated that a change in travel direction change no longer can beexecuted, interacts with the locking device (12) which locks theselector lever (5) in its existing position, upon occurrence of thedisturbance of a signal transmission, during for the emergency operatingmode of the automatic transmission (2).
 4. The transmission/enginecontrol for a motor vehicle with an automatic transmission according toclaim 1, wherein the warning apparatus (3) has one of an opticaladvisory apparatus and an acoustic advisory apparatus which notifies thedriver by one of an optical signal and an acoustic signal, uponinitiation of the emergency operating mode of the automatic transmission(2) due to the occurrence of the disturbance of the signal transmission,that the change in travel direction no longer can be executed.
 5. Thetransmission/engine control for a motor vehicle with an automatictransmission according to claim 1, wherein, in the case of one of: adisturbance, a dropout of an electronic transmission control apparatus(9), a dropout of a CAN-data base, and a dropout of the positionrecognition apparatus (4) of the selector lever (5), the application ofthe emergency operating mode is made known.
 6. The transmission/enginecontrol for a motor vehicle with an automatic transmission according toclaim 1, wherein the electronic transmission controller normally outputsan output signal which denotes normal operation, and the emergencyoperating mode is recognized when the warning apparatus (3) indicates anabsence of the output signal outputted by the electronic transmissioncontroller.
 7. The transmission/engine control for a motor vehicle withan automatic transmission according to claim 1, wherein the warningapparatus (3) remains active at least for a predetermined period afterthe occurrence of the disturbance and operation under the emergencyoperating mode of the vehicle.
 8. The transmission/engine control for amotor vehicle with an automatic transmission according to claim 1,wherein the transmission independent processing unit (6), in which theprogram module of the of the warning apparatus (3) is integrated, is aseparate processor.
 9. The transmission/engine control for a motorvehicle with an automatic transmission according to claim 1, wherein thetransmission independent processing unit (6), in which the programmodule of the of the warning apparatus (3) is integrated, is a componentof the motor control (7).
 10. The transmission/engine control for amotor vehicle with an automatic transmission according to claim 1,wherein the transmission independent processing unit (6), in which theprogram module of the of the warning apparatus (3) is integrated, is acomponent of the control apparatus (10) of the vehicle brake system. 11.The transmission/engine control for a motor vehicle with an automatictransmission according to claim 1, wherein at least one of: the maximummotor torque; the maximum motor speed; and activation of the braking ofthe vehicle brake system is provided in such a manner that the vehiclespeed, upon startup from rest, while in the emergency operating mode,corresponds to a creeping velocity of the vehicle.
 12. Thetransmission/engine control for a motor vehicle with an automatictransmission according to claim 2, wherein the vehicle brakes areelectrically controlled.
 13. The transmission/engine control for a motorvehicle with an automatic transmission according to claim 3, wherein thelocking device (12) is a magnet which, when supplied with electricalcurrent, fixes the selector lever (5) in its existing position.
 14. Thetransmission/engine control for a motor vehicle with an automatictransmission according to claim 3, wherein the locking device (12) isconstructed as a magnet which, when a supplied of electrical currentthereto is interrupted, fixes the selector lever (5) in its existingposition.